What determines conditionality in ant–Hemiptera interactions? Hemiptera habitat preference and the role of local ant activity

Abstract.  1. This paper describes spatial variation in density of a mutualist Hemiptera, and attempts to elucidate an understanding of the spatial variation in conditionality of its mutualism with ants.
2. Aggregations of the membracid treehopper, Campylenchia sp., occurred more frequently, and with higher number of individuals, in isolated trees as compared with their occurrence in the same tree species in wooded patches.
3. Using treehopper aggregations as the level of replication, there was a habitat × ant presence interaction associated with colony survival time. However, when the median survival time of all aggregations within each tree was used, only an additive effect of both habitat type and ant presence were apparent. This suggests that treehopper aggregations in some isolated trees experienced more benefit from ant presence than other trees.
4. The ant:treehopper ratio averaged over each tree was correlated with effect of ant presence on survivorship (survival time without ants/survival time with ants). Therefore, conditionality in the ant–membracid mutualism appears related to ant attendance level at the scale of individual trees.
5. Ant attendance at treehopper aggregations in isolated and matorral trees did not differ, and therefore there is no clear mechanism by which ants create the contrast in treehopper densities between the two habitat types.
6. The main force shaping initial treehopper densities in the two habitats is likely plant quality. Results suggest that growing situation (or more specifically plant health) is likely a good predictor of membracid density, while general ant activity within a tree is the best indicator of interaction strength.     

Of glaciers and refugia: a decade of study sheds new light on the phylogeography of northwestern North America

Glacial cycles have played a dominant role in shaping the genetic structure and distribution of biota in northwestern North America. The two major ice age refugia of Beringia and the Pacific Northwest were connected by major mountain chains and bordered by the Pacific Ocean. As a result, numerous refugial options were available for the regions taxa during glacial advances. We reviewed the importance of glaciations and refugia in shaping northwestern North America’s phylogeographic history. We also tested whether ecological variables were associated with refugial history. The recurrent phylogeographic patterns that emerged were the following: (i) additional complexity, i.e. refugia within refugia, in both Beringia and the Pacific Northwest; and (ii) strong evidence for cryptic refugia in the Alexander Archipelago and Haida Gwaii, the Canadian Arctic and within the ice‐sheets. Species with contemporary ranges that covered multiple refugia, or those with high dispersal ability, were significantly more likely to have resided in multiple refugia. Most of the shared phylogeographic patterns can be attributed to multiple refugial locales during the last glacial maximum or major physiographic barriers like rivers and glaciers. However, some of the observed patterns are much older and appear connected to the orogeny of the Cascade‐Sierra chain or allopatric differentiation during historic glacial advances. The emergent patterns from this review suggest we should refine the classic Beringian‐southern refugial paradigm for northwestern North American biota and highlight the ecological and evolutionary consequences of colonization from multiple refugia.     

Diversification of coordination patterns during feeding behaviour in cheiline wrasses

Successful fish feeding often requires the coordination of several complex motor and sensory systems to ensure that food is accurately detected, approached, acquired, and consumed. In the present study, we address feeding behaviour as a coordinated set of multiple, facultatively independent, anatomical systems. We sought to determine whether the patterns of interaction between trophic, locomotor, and oculomotor systems are associated with changes in morphology and ecology within a closely-related, but trophically divergent, group of fishes. We present a quantitative kinematic analysis of skull motion, locomotor behaviour, and oculomotor responses during feeding to assess coordination in three functional systems directly involved in feeding. We use coordination profiles to depict the feeding behaviours of three carnivorous coral reef fishes of the tribe Cheilinini in the family Labridae (the wrasses): Cheilinus fasciatus (a slow-swimming predator of benthic invertebrates), Epibulus insidiator (a slow-stalking predator with extraordinary jaw protrusion), and Oxycheilinus digrammus (a fast-attack predator). Differences were detected in several variables relating to jaw, body, fin, and eye movements. Overall patterns of coordination were more similar between E. insidiator and O. digrammus , which are capable of capturing elusive prey, than between C. fasciatus and E. insidiator , which are the two most closely-related species among the three. Evidence for the evolution of coordination patterns among cheiline fishes suggests that the sensory-motor systems involved in processing stimuli and coordinating a physical response during feeding have changed considerably, even among closely-related species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 289–308.     

Response of Brown Treesnakes to Reduction of Their Rodent Prey

ABSTRACT Trapping brown treesnakes (Boiga irregularis; BTS) with live-mouse (Mus domesticus) lures is the principal control technique for this invasive species on Guam. Lure-based trapping is also used on other islands as a precaution against undetected arrivals and in response to verified BTS sightings. However, the effectiveness of lure-based trapping on other islands is questionable, as it has yielded no BTS despite other evidence of their presence. Some evidence suggests that high rodent numbers may interfere with BTS control. To test the relationship between rodent abundance and snake trappability, we conducted a controlled, replicated field experiment incorporating a rodenticide treatment during a BTS mark-recapture study. Using open population modeling in Program MARK, we estimated BTS apparent survival and recapture probabilities. Rodent reduction increased BTS recapture probabilities by 52–65% in 2002 and 22–36% in 2003, and it decreased apparent survival by < 1% both years. This appears to be the first published instance of manipulating wild prey to influence snake behavior. Rodent reduction may enhance detection and control of BTS with traps on Guam and other islands. It may also amplify the effectiveness of oral toxicants against BTS.     

Small-Mammal Microhabitat Associations and Response to Grazing in Oregon

Abstract: Livestock grazing is common and widespread throughout North America, yet few studies have evaluated its effects on small mammals. We studied small mammals in mixed-conifer forests and oak woodlands on the Cascade-Siskiyou National Monument in southern Oregon, USA, to 1) evaluate small-mammal microhabitat associations, 2) identify riparian-associated species, and 3) test the hypothesis that grazing does not influence small mammals after accounting for microhabitat associations. We live-trapped small mammals at 16 study sites and used logistic regression to model probability of capture on measured habitat characteristics at each trap station and to evaluate effects of grazing. Over 2 years, we trapped 1,270 individual small mammals representing 18 species. Odds of capturing western harvest mice (Reithrodontomys megalotis), dusky-footed woodrats (Neotoma fuscipes), and long-tailed voles (Microtus longicaudus) were lower (P < 0.05) on heavily versus lightly grazed sites. Odds of capture for deer mice (Peromyscus maniculatus) were lower (P < 0.05) on heavily versus lightly grazed sites in woodlands, but there was less difference in the odds of capture between grazing intensities in conifer forests. Odds of capturing Townsend's vole (Microtus townsendii) were lower on heavily versus lightly grazed riparian areas. Western harvest mice, long-tailed voles, and Townsend's voles were associated with, but not obligated to, riparian areas. Deer mice were ubiquitous, but captures were also higher (P < 0.05) in riparian areas compared with uplands. Siskiyou chipmunks (Tamias siskiyou) and piñon mice (Peromyscus truei) were associated with uplands (P < 0.05) rather than riparian areas. Trowbridge's shrews (Sorex trowbridgii), Siskiyou chipmunks, and bushy-tailed woodrats (Neotoma cinerea) were positively associated with coarse woody debris. Land managers should anticipate that small mammals associated with herbaceous or shrub cover, particularly in riparian areas, will decline when cattle remove this cover.     

Galanthus trojanus: a new species of Galanthus (Amaryllidaceae) from north-western Turkey

Galanthus trojanus , a new species endemic to north-western Turkey, is described and illustrated. The morphological differences between the new species and two similar species, G. nivalis and G. rizehensis , are discussed.     

On the systematic status of the desert plated lizard (Angolosaurus skoogi): phylogenetic inference from DNA sequence analysis of the African Gerrhosauridae

The desert plated lizard ( Angolosaurus skoogi ), a 'sand sea' endemic of the northern Namib Desert, exhibits remarkable morphological convergence with other dune-dwelling lizards worldwide. This distinct ecomorphic condition sets Angolosaurus apart from the remaining genera in the family Gerrhosauridae. Indeed, a morphological phylogeny addressing generic relationships within the Cordyliformes (Cordylidae + Gerrhosauridae) identified Angolosaurus as the earliest diverging taxon among African gerrhosaurids. We re-evaluated the basal status of Angolosaurus , conducting a molecular phylogenetic analysis of the African and Madagascan gerrhosaurid genera. Our survey involved a comprehensive species-level comparison among the four nominal genera of mainland Africa ( Angolosaurus , Cordylosaurus , Tetradactylus and Gerrhosaurus ). Mitochondrial DNA sequence data from the cytochrome b , ND2, 12S and 16S rRNA genes were combined for analysis using both parsimony and maximum likelihood procedures. In contrast to the morphological hypothesis, our results do not depict Angolosaurus as the sister taxon to other African gerrhosaurids. Rather, the molecular analyses consistently place Angolosaurus within Gerrhosaurus , rendering the latter genus paraphyletic.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 253–261.